In this study, we investigated the physicochemical properties and composition of monosaccharidex from Polygonatum sibiricum. Simultaneously, we explored the in vivo and in vitro immunomodulatory activity and mechanism of Polygonatum sibiricum polysaccharide (PSP) activity by monitoring changes in immune organs, immune cells, and cytokines. The average molecular weight (Mw) of PSP was 9.514 × 104 Da. The monosaccharide components of PSP were galactose, rhamnose, arabinose, mannose, and glucose at a molar ratio of 11.72 : 1.78 : 4.15 : 1.00 : 2.48. PSP increased thymus and spleen indices, enhance the proliferative responses of splenocytes, and increased the phagocytosis of mononuclear macrophages. Simultaneously, PSP could recover the body mass of immunosuppressed mice, and increased blood erythrocyte counts in the sera of cyclophosphamide (Cy)-treated and normal mice, whilst blood leukocytes and platelet counts of Cy-treated mice recovered. PSP elevated the CD4+/CD8+ ratio is a dose-dependent manner and increased the levels of interleukin-2 (IL-2) and tumor necrosis factor-α (TNF-α) in the sera of Cy-treated mice. PSP further enhanced the expression of IL-2 and TNF-α in spleen lymphocytes. Additionally, PSP treatment accelerated the recovery of natural killer cell activity in a dose-dependent manner. Taken together, PSP not only regulated the immune function of normal mice, but participated in the protection against immunosuppression in Cy-treated mice, highlighting its potential as an immunostimulant.

Polygonatum sibiricum first appeared in ancient Chinese medicine books around 1000 years ago
and is used to tonify the spleen and nourish the lungs. The authors present here a kind of natural polysaccharides (PSP) extracted
from Polygonatum sibiricum were purified, characterized and assayed both
in vitro and in vivo for its immunomodulatory activity and
mechanism. It is of interest to note that PSP not only regulated the immune
function of normal mice, but participated in the protection against
immunosuppression in cyclophosphamide-treated mice, highlighting its potential as an immunostimulant.

Danshensu
(3-(3,4-dihydroxyphenyl)-(2R)-lactic acid) is one of the water-soluble active
ingredients of Salvia miltiorrhizae, a
traditional Chinese medicine for the treatment of cardiovascular diseases. This
study investigated the protective effects of Danshensu on the acute liver
injury induced by iron overload in mice. The results indicated that the underlying
mechanisms at least partly involve anti-oxidation, anti-inflammation,
anti-apoptosis, and decreasing hepatic iron deposition possibly through
down-regulating the expression of iron uptake related proteins, such as DMT1,
TfR, and L-type Ca2+ CP α1C. Therefore, they
conclude Danshensu could be a promising prophylactic or therapeutic agent
for iron overload diseases.

The interaction of human leukocyte antigen (HLA) with specific drugs is associated with delayed-type hypersensitivity reactions, which cause severe cutaneous toxicity. Such interactions induce structural alterations in HLA complexes via several different mechanisms such as the hapten theory, p-i concept, and altered peptide repertoire model, leading to the activation of cytotoxic T cells. To date, comprehensive detection of such structural alterations in preclinical studies has been difficult. Here, we evaluated structural alterations in HLA complexes focusing on the interaction between the HLA-B*57 : 01 allele and abacavir (an anti-human immunodeficiency virus drug), representing a model of abacavir hypersensitivity syndrome induced by changes in the peptide repertoire on the HLA molecule. We employed a phage display method using a commercially available antibody library to screen specific phage antibodies able to recognize HLA-B*57 : 01. The affinity of selected phage antibodies increased because of structural alterations in HLA-B*57 : 01 following exposure to abacavir, indicating that specific phage antibodies can identify drug-mediated structural changes in HLA complexes. We also identified an unreported structural change in HLA-B*57 : 01 using the phage display method, whereby abacavir increased the expression of peptide-deficient HLA-B*57 : 01 on the cell surface. These results suggest that phage display technology is a useful method for detecting structural changes in HLA complexes. This technology represents a potential novel strategy for predicting HLA-associated hypersensitivity reactions by drugs in pre-clinical studies.

Efficiency (speed and cost) and animal welfare are important factors in the development of new drugs. A novel method (the half-life method) was developed to predict the human plasma concentration–time profile of a monoclonal antibody (mAb) after intravenous (i.v.) administration using less data compared to the conventional approach; moreover, predicted results were comparable to conventional method. This new method use human geometric means of pharmacokinetics (PK) parameters and the non-human primates (NHP) half-life of each mAb. PK data on mAbs in humans and NHPs were collected from literature focusing on linear elimination, and the two-compartment model was used for analysis. The following features were revealed in humans: 1) the coefficient of variation in the distribution volume of the central compartment and at steady state of mAbs was small (22.6 and 23.8%, respectively) and 2) half-life at the elimination phase (t1/2β) was the main contributor to plasma clearance. Moreover, distribution volume showed no significant correlation between humans and NHPs, and human t1/2β showed a good correlation with allometrically scaled t1/2β of NHP. Based on the features revealed in this study, we propose a new method for predicting the human plasma concentration–time profile of mAbs after i.v. dosing. When tested, this half-life method showed reasonable human prediction compared with a conventional empirical approach. The half-life method only requires t1/2β to predict human PK, and is therefore able to improve animal welfare and potentially accelerate the drug development process.

Efficiency
and animal welfare are important factors in the development of new drugs.
Considering this, Nakamura et al.
propose a new way of predicting human PK for mAbs that is more efficient than
conventional methods. By collecting mAb PK data on linear elimination and
analyzing a two-compartment model, they revealed that half-life during
elimination is the main contributor to plasma clearance. Based on this feature,
they developed a novel method that uses easy-to-obtain parameters from humans
and non-human primates to predict human PK. Called the half-life method, it can
improve animal welfare and potentially accelerate the drug development process.

Ethenzamide (ETZ), an antipyretic analgesic categorized as a non-steroidal anti-inflammatory drug (NSAID), is widely used as an OTC drug in combination with other NSAIDs. However, its site of action and mechanism underlying its analgesic action have not yet been fully elucidated. In this study, we performed in vitro pharmacological assays to identify the mechanism underlying the analgesic action of ETZ, and also conducted the rat formalin test to investigate its analgesic effect and site of action. Of the 85 receptors, ion channels, transporters and enzymes tested, we found that ETZ binds to the 5-hydroxytryptamine (5HT)2B receptor in concentration-dependent manner with modest inhibitory effects on monoamine oxidase-A and transient potential vanilloid 1 channel. The 5HT2B receptor antagonist activity of ETZ was also confirmed in a cellular functional assay. Furthermore, the drug exerted no inhibitory effects on cycrooxygenase-1 and -2. In the rat formalin test, oral administration of ETZ significantly reduced the nociceptive responses of the second phase and also the number of c-Fos-expressing cells in the spinal dorsal horn, in a dose-dependent manner. Moreover, intrathecal administration of ETZ significantly reduced the nociceptive responses. These results suggest that the analgesic effect of ETZ is exerted at least in the spinal cord, and the effect would be attributed to multiple mechanisms of action including 5HT2B receptor blockade.

Ethenzamide
(ETZ) is widely used as an OTC pain reliever, however, its site of action and
mechanism underlying its analgesic action had not yet been fully elucidated.
The article by Nikaido et al. provides evidence suggesting that the
analgesic effect of ETZ in the rat formalin test was mediated by multiple
mechanisms of action including the 5-hydroxytryptamine2B receptor
blockade at the spinal cord.

Pathological angiogenesis is a leading cause of blindness in several retinal diseases. The key driving factor inducing pathological angiogenesis is the pronounced hypoxia leading to a marked, increased production of vascular endothelial growth factor (VEGF). The aim of this study was to determine whether the abnormal vascular growth occurs in a manner dependent on the degree of the vascular defects. Vascular defects of two different degrees were created in the retina by subcutaneously treating neonatal rats with the VEGF receptor (VEGFR) tyrosine kinase inhibitor KRN633 on postnatal day (P) 4 and P5 (P4/5) or P7 and P8 (P7/8). The structure of the retinal vasculature changes was examined immunohistochemically. Prevention of vascular growth and regression of some preformed capillaries were observed on the next day, after completion of each treatment (i.e., P6 and P9). The vascular regrowth occurred as a result of eliminating the inhibitory effect on the VEGFR signaling pathway. KRN633 (P4/5)-treated rats exhibited a retinal vasculature with aggressive intravitreal neovascularization on P21. On the other hand, the appearance of tortuous arteries is a representative vascular pathological feature in retinas of KRN633 (P7/8)-treated groups. These results suggest that an interruption of the retinal vascular development at different time points induces different vascular pathological features in the retina. Pharmacological agents targeting the VEGF signaling pathway are useful for creating an abnormal retinal vasculature with various pathological features in order to evaluate the efficacy of anti-angiogenic compounds.

Pathological
angiogenesis is a leading cause of blindness in several retinal diseases. Kondo
et al. demonstrated that only a 2-day treatment of neonatal rats with the VEGF
receptor tyrosine kinase inhibitor at different time points could induce
abnormal blood vessels with different vascular pathological features (intravitreal
neovascularization vs. tortuous arteries) in the retina. Pharmacological agents
targeting the VEGF signaling pathway are useful for creating an abnormal
retinal vasculature with various pathological features in order to study the
mechanisms underlying abnormal retinal angiogenesis and evaluate the efficacy
of anti-angiogenic compounds.

The objective of this study was to evaluate the influence of cancer cachexia on pain control in cancer patients receiving a transdermal fentanyl patch (FP) and to investigate whether dry skin was a factor related to cancer cachexia and uncontrolled pain. We retrospectively reviewed the medical records of 77 patients receiving FP treatment for the first time, who were classified into cancer cachexia and non-cancer-cachexia groups, according to European Palliative Care Research Collaborative criteria. On day 7 after FP administration, the mean FP dose and morphine equivalent dose (MED) in the cancer cachexia group were significantly higher than in the non-cancer-cachexia group. Additionally, in the cancer cachexia group, there was a significantly larger degree of variation in pain intensity over 7 d than in the non-cachexia group. In patients who were switched from FP to morphine injection, the mean pain intensity and MED on day 3 after morphine injection were significantly lower than those immediately before morphine injection. Subsequently, to investigate whether dry skin was involved in poor pain control in the cancer cachexia group, transepidermal water loss (TEWL) was compared between 15 additional patients classified into cancer cachexia and non-cancer cachexia groups; the mean TEWL in the cancer cachexia group was found to be significantly lower. Our data suggest that cancer cachexia may be a risk factor for poor pain control in patients receiving FP treatment, and that uncontrolled pain in FP treatment may be caused by the inhibition of fentanyl transdermal absorption due to dry skin.

The transdermal
fentanyl patch (FP) has been used worldwide to relieve cancer pain. However, no
previous studies have examined the influence of cancer cachexia on pain control
in cancer patients receiving FP treatment. Chiba et al. found that cancer
cachexia may be a risk factor for poor pain control in patients receiving FP
treatment, and that uncontrolled pain in FP treatment may be caused by the
inhibition of fentanyl transdermal absorption due to dry skin.

Bone loss and bone-related disease are associated with the deregulation of osteoclast function, and therefore agents that affect osteoclastogenesis have attracted attention. The purpose of the present study was to discover modified kavalactone analogs as potential anti-osteoclastogenic agents. We assessed the effect of 26 analogs on osteoclast differentiation in vitro. The most potent compound, (E)-6-(2-fluorostyryl)-4-methoxy-2H-pyran-2-one (22), suppressed receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenic differentiation of RAW264 cells with IC50 values of 4.3 µM. A partial structure–activity relationship study revealed the importance of fluorine and its position within the 5,6-dehydrokawain skeleton. The results of a pit formation assay suggested that compound 22 prevents osteoclastic bone resorption by inhibiting osteoclastogenesis. Moreover, compound 22 downregulated mRNA expression levels of RANKL-induced nuclear factor of activated T cells c1 (NFATc1) and osteoclastogenesis-related genes. These results suggest that (E)-6-(2-fluorostyryl)-4-methoxy-2H-pyran-2-one scaffold could lead to the identification of new anti-resorptive agents.

To discover small molecules that affect
osteoclastogenesis, Kumagai et al designed and synthesized styrylpyrone
analogs, and discovered (E)-6-(2-fluorostyryl)-4-methoxy-2H-pyran-2-one (22) has osteoclast-inhibitory activities in murine RAW264 cells. A
partial structure-activity relationship revealed that fluorine and its position
within the styrylpyrone skeleton were important. Authors also revealed that compound
22 prevents osteoclastic bone
resorption by inhibiting osteoclastogenesis. Compound 22 downregulated mRNA expression levels of RANKL-induced nuclear
factor of activated T cells c1 (NFATc1) and osteoclastogenesis-related genes.
These findings may be useful for the desigh of antiresorptive agents for the
treatment of bone disorders characterized by excessive osteoclastic activity .

The 34th Annual Meeting of the Academy of
Pharmaceutical Sciences and Technologies, Japan (APSTJ) was held in Toyama,
Japan, May 16–18, 2019. In this meeting, a joint
symposium was held with the Pharmaceutical Society of Japan and APSTJ.
The theme of the symposium was “Recent Advances in Research on Particulate
Formulations such as Lipoproteins, Liposomes, Extracellular Vesicles, and iPS
Derived Cells.” The four invited speakers provide their review articles in the Current Topics of this
issue.

We previously showed that adhesive aggregates were formed when levofloxacin hydrate tablets and lansoprazole orally disintegrating (OD) tablets were suspended in water in the clinical context. In this study, we have clarified the factors causing aggregate formation, focusing on the role of pharmaceutical additives and electrostatic interaction. Co-suspension of enteric-coated proton pump inhibitor (PPI) esomeprazole magnesium hydrate with levofloxacin resulted in aggregate formation, whereas the non-enteric-coated PPI vonoprazan fumarate did not. A comparison of pharmaceutical additive in the two PPIs highlighted polysorbate 80 and methacrylic acid copolymer LD as candidates causing aggregation. When these pharmaceutical additives were added to levofloxacin, only methacrylic acid copolymer LD induced aggregate formation. Since levofloxacin is zwitterionic, we examined another zwitterionic ingredient, ampicillin sodium, and found that it also formed aggregates with methacrylic acid copolymer LD, while benzylpenicillin sodium, which is not zwitterionic, did not form aggregates. When we next examined a series of zwitterionic quinolone antimicrobial drugs, we found that ofloxacin, which is highly soluble, formed aggregates with lansoprazole OD tablets, whereas poorly soluble quinolone antimicrobial drugs did not form aggregates. Further, although cefepime hydrochloride and cephalexin did not form aggregates with methacrylic acid copolymer LD in tap water, aggregates were formed when a suspension of cefepime hydrochloride or cephalexin with methacrylic acid copolymer LD was adjusted to pH 7.0. Our results indicate that electrostatic interaction between zwitterionic ingredients and methacrylic acid copolymer LD can result in aggregate formation under conditions where the drug and methacrylic acid copolymer LD are both sufficiently soluble.

Interactions between drugs and
pharmaceutical additives can cause problems when mixing multiple drugs in
clinical settings. One example is aggregate formation between levoﬂoxacin
hydrate tablets and lansoprazole orally disintegrating tablets. Nakagawa et al
investigated the factors involved in this aggregation, focusing on the role of
pharmaceutical additives and electrostatic interaction. Levoﬂoxacin, which is
zwitterionic, formed aggregates with methacrylic acid copolymer LD, one of the pharmaceutical
additives of lansoprazole orally disintegrating tablet. Other zwitterionic
ingredients, including ampicillin, meropenem, cefepime, and cephalexin, also formed
aggregates with methacrylic acid copolymer LD.

Sesamin is a major lignan in sesame seeds, and a recent meta-analysis of controlled trials indicated that sesamin intake decreases blood pressure. The antihypertensive effect of sesamin has been suggested to be due to sesamin-mediated suppression of 20-hydroxyeicosatetraenoic acid production catalyzed by CYP4F2. However, the detailed mechanism underlying inhibition of CYP4F2 function by sesamin remains unclear. In this study, the effects of sesamin on catalytic activity of CYP4F2 were investigated in vitro. Sesamin inhibited luciferin-4F2/3 O-dealkylase activity of recombinant human CYP4F2 with an IC50 value of 0.381 µM. When preincubated in the presence of reduced nicotinamide adenine dinucleotide phosphate (NADPH) for 20 min, sesamin potentiated the inhibition of CYP4F2 activity. Moreover, kinetic analysis of the inactivation revealed that sesamin showed a preincubation time- and concentration-dependent inhibition of CYP4F2 activity yielding a maximal inactivation rate constant (kinact) value of 0.354 min−1 and half-maximal inhibitory concentration (KI) value of 1.12 µM. The inactivation of CYP4F2 by sesamin required NADPH. These results indicated that sesamin is a mechanism-based inactivator of human CYP4F2.

Sesamin is a
major lignan in sesame seeds, and a
recent meta-analysis of controlled trials showed that sesamin consumption reduces blood pressure. The
antihypertensive effect of sesamin was suggested to
be caused by suppression of cytochrome P450 4F2 (CYP4F2)-mediated 20-hydroxyeicosatetraenoic
acid production. However, the detailed mechanism underlying inhibition
of CYP4F2 function by sesamin was
unclear. The article by Watanabe et al.
characterized the in vitro inhibitory effects of sesamin on human CYP4F2 activity. The results indicated
that sesamin is a
mechanism-based inactivator of CYP4F2.

5-Aminosalicylic acid (5-ASA) is used as first line therapy for symptom remission and maintenance of inflammatory bowel disease (IBD). Because 5-ASA is well absorbed from the small intestine when orally administered, several 5-ASA formulations for selective delivery to the colon have been developed and used in clinical practice. However, its delivery efficiency to local inflamed colonic sites remains low. Intestinal H+-coupled oligopeptide transporter 1 (PEPT1) expression in the colon is low, whereas its expression is induced in the colon under chronic inflammation conditions, such as IBD. Therefore, we considered that PEPT1 would be a target transporter to improve 5-ASA delivery efficiency to local colonic lesions. We evaluated the transport characteristics of dipeptide-like 5-ASA derivatives, which were coupling glycine (Gly), lysine, glutamic acid (Glu), valine (Val) and tyrosine to amino or carboxyl group of 5-ASA, in Caco-2 cells. [3H]Glycylsarcosine (Gly-Sar) uptake into Caco-2 cells was inhibited by all 5-ASA derivatives. In addition, 5-ASA derivatives (Gly-ASA, Glu-ASA and Val-ASA), which were coupled by glycine, glutamic acid and valine to amino group of 5-ASA, were taken up in a pH- and concentration-dependent manner and their uptake was inhibited by excess Gly-Sar. Two-electrode voltage-clamp experiment using human PEPT1 expressing Xenopus oocytes showed that Gly-ASA, Glu-ASA and Val-ASA induced marked currents at pH 6.0. Taken together, these results showed that these 5-ASA derivatives are transportable substrates for PEPT1.

5-Aminosalicylic acid (5-ASA) is used as
first line therapy for inflammatory bowel disease (IBD). However, a very high
5-ASA dose is required for IBD treatment because 5-ASA formula is relatively
low delivery efficacy to local inflamed colonic sites. In this report, Yuri et
al. focused on an intestinal H+-coupled oligopeptide transporter
1 (PEPT1) which is induced in the colon under IBD condition, and demonstrated
that the newly synthesized dipeptide-like 5-ASA derivatives, which are coupling
glycine, glutamic acid and valine to amino group of 5-ASA, were transportable
substrates for PEPT1.

Cutting-edge contributions from invited poster
presentations providing significant research works in the fifth International
Symposium for Medicinal Sciences (ISMS) in the 139th Chiba annual meeting in
2019 are assembled for the Current Topics section in this issue of the Biological
and Pharmaceutical Bulletin.

Resveratrol (Res) is a natural active antioxidant that is effective in relieving inflammatory bowel disease (IBD). However, the specific mechanism for its function is unknown. In our study, dextran sodium sulfate (DSS)-induced mouse IBD disease model was constructed. All mice were randomly divided into three groups. The treatment effects of resveratrol on IBD were evaluated by observing the body weight, fecal traits, colon/spleen gross appearance, tissue hematoxylin–eosin (H&E)/immunohistochemistry (IHC) and inflammatory factors. The expression of small ubiquitin-like modifier protein 1 (SUMO1) and its Wnt/β-catenin pathway-related genes was analyzed by IHC, Western blot, Real-time PCR (RT-PCR) and Immunofluorescence. The outcome indicated that resveratrol treatment significantly relieved the symptoms of IBD. The expression level of anti-inflammatory cytokines was increased while that of pro-inflammatory cytokines was decreased in both colon and spleen tissues of resveratrol-treated mice. SUMO1 expression and Wnt/β-catenin pathway were suppressed in colon and spleen tissues of IBD mice treated with resveratrol. In addition, we provided evidence that resveratrol inhibited SUMO1 and β-catenin expression and their nuclear localization in human colonic epithelial cell line (FHC). Moreover, we found that SUMO1 and β-catenin had higher expression levels in colorectal cancer patients than in health and colitis patients. In conclusions, resveratrol alleviates DSS-induced IBD by modulating SUMO1 through Wnt/β-catenin pathway.

Mao et al. found that
resveratrol can significantly inhibit the expression of SUMO1. They demonstrate
that resveratrol alleviates inflammatory bowel disease (IBD) in mice by inhibiting
the expression of SUMO1 molecule, and by modulating the activation of wnt/β-catenin
signaling pathway. Clinical analysis also proves that the expression of SUMO1
and β-catenin molecules increased with the worsening of the disease, which also
provides a new method for clinical diagnosis and treatment of IBD.

Edoxaban is used to prevent and treat stroke or systemic embolism such as venous thromboembolism. Although bleeding is the most common complication of anticoagulants, only a few studies have addressed the safety of direct oral anticoagulants in East Asian patients. In this study, we investigated the risk factors for bleeding in Japanese patients receiving edoxaban. A retrospective review of the records of 198 patients who received 30 mg/d edoxaban in our hospital between April 2015 and March 2017 was performed. Subsequently, these patients were followed up to 1 year. Seven (3.5%) and 22 (11.1%) patients developed major bleeding and clinically relevant bleeding, respectively. In the univariate Cox regression analyses, low baseline hemoglobin levels (p = 0.002) and low baseline creatinine clearance (p = 0.020) were significantly associated with major bleeding. Multivariate Cox regression analysis revealed that a low baseline hemoglobin level was a significant risk factor for major bleeding and clinically relevant bleeding [hazard ratio 1.67 per 1 g/dL decrease (95% confidence interval 1.14–2.56, p = 0.008) and hazard ratio 1.31 per 1 g/dL decrease (95% confidence interval 1.06–1.62, p = 0.013), respectively]. Baseline hemoglobin level in quartiles also showed a quartile-dependent decrease in major bleeding and clinically relevant bleeding event. These results suggest that low baseline hemoglobin level is a significant risk factor for both major bleeding and clinically relevant bleeding in Japanese patients receiving edoxaban. Thus, these patients should be carefully monitored.

Edoxaban is an oral
anticoagulant used for preventing and treating stroke or systemic embolism. Bleeding
is the most common complication associated with anticoagulants. In particular,
severe bleeding is assumed to be related to
mortality in patients treated with anticoagulation
therapy. However, few studies have examined the risk factors for bleeding in
Japanese patients receiving edoxaban. The article by Takase et al. revealed
that a low baseline hemoglobin level was a significant risk factor for major and clinically relevant bleeding in Japanese patients receiving edoxaban.

It is therapeutically important to elucidate the factors involved in the radiation resistance of tumors. We previously showed that ATP is released from mouse melanoma B16 cells in response to γ-irradiation, but the role of adenosine, a metabolite of ATP, is still unclear. Here, we show that the adenosine A2B receptor is involved in DNA damage repair and radioresistance in mouse melanoma B16 cells. The DNA damage response after γ-irradiation was attenuated by pretreatment with A2B receptor antagonists, such as PSB603, while it was enhanced by pretreatment with A2B receptor agonists, such as BAY60-6583. γ-Irradiation decreased the cell survival rate, and pretreatment with PSB603 further reduced the survival rate. On the other hand, pretreatment with BAY60-6583 increased the cell survival rate after irradiation. The DNA damage response and the cell survival rate after γ-irradiation were both decreased in A2B-knockdown cells. In vivo experiments in mice confirmed that tumor growth was suppressed and delayed in the irradiated group pretreated with PSB603, compared with the irradiation-alone group. Our results indicate that adenosine A2B receptor contributes to radioresistance, and could be a new target for the development of agents to increase the efficacy of radiotherapy.

The article by Tanaka et al. proposed a novel
mechanism of radioresistance and candidate for use as radiosensitizers in
radiation therapy of melanoma. A2B receptor was involved in radioresistance via
DNA damage response in B16 cells. A2B receptor antagonist enhances tumor growth-inhibitory
effect by gamma-ray and shows radiosensitizing effect in vivo. These
findings proposed that A2B receptor contributes to radioresistance, and could be a new target for the development of
agents to increase the efficacy of radiotherapy.

CD81 is a highly conserved four-transmembrane protein in mammals and widely expressed on many tissues. It belongs to the tetraspanin family and forms complexes with various cell surface membrane proteins. It also functions in cell migration and B-cell activation, which is induced by CD81 complexing with CD19, CD21 and the B-cell receptor. Thus, CD81 is thought to play a key role in regulating cell function and fate. However, little is known about the degradation mechanism of CD81. Here we found that CD81 on the plasma membrane is degraded by the lysosome pathway via endocytosis. The expression levels of CD81 in HEK293T cells treated with a proteasome inhibitor (lactacystin) and lysosome inhibitors (chloroquine and bafilomycin A1) were analyzed by flow cytometry. The expression of CD81 on the cell surface was increased by the lysosome inhibitors, but not lactacystin. A pulldown assay revealed that CD81 was conjugated with a K63- and K29-linked poly-ubiquitin chain before its degradation, and the poly-ubiquitination site was Lys8 at the N-terminal intracellular domain of CD81. Furthermore, mutant CD81, in which Lys8 was substituted with alanine (Ala), extended the CD81 half-life compared with wildtype. CD81 was mainly localized on the plasma membrane in normal cells, but also co-localized with lysosomal LAMP1 and early endosomal EEA1 in chloroquine-treated cells. Furthermore, a clathrin-mediated endocytosis inhibitor, chlorpromazine, stabilized CD81 expression on the cell surface. Hence, we demonstrated that CD81 is internalized by clathrin-mediated endocytosis and subsequently degraded via a lysosome pathway requiring the K63- and K29-linked poly-ubiquitination of CD81.

CD81
is important for regulating biological processes such as B cell receptor
signaling and B cell differentiation. However, little is known about degradation
mechanism of CD81. Hosokawa et al. demonstrated that CD81 on the cell surface is
degraded by lysosome via K63- and K29-linked poly-ubiquitination. The poly-ubiquitinated
CD81 is translocated from the cell surface into endosomes and is degraded by
lysosomes. This is the first report showing that the lysosomal degradation of
CD81 requires poly-ubiquitination
and clathrin-mediated endocytosis.

Acetaminophen (paracetamol, N-acetyl-p-aminophenol; APAP) is the most popular analgesic/antipyretic agent in the world. APAP has been regarded as a safer drug compared with non-steroidal anti-inflammatory drugs (NSAIDs) particularly in terms of lower risks of renal dysfunction, gastrointestinal injury, and asthma/bronchospasm induction, even in high-risk patients such as the elderly, children, and pregnant women. On the other hand, the recent increasing use of APAP has raised concerns about its toxicity. In this article, we review recent pharmacological and toxicological findings about APAP from basic, clinical, and epidemiological studies, including spontaneous drug adverse events reporting system, especially focusing on drug-induced asthma and pre-and post-natal closure of ductus arteriosus. Hepatotoxicity is the greatest fault of APAP and the most frequent cause of drug-induced acute liver failure in Western countries. However, its precise mechanism remains unclear and no effective cure beyond N-acetylcysteine has been developed. Recent animal and cellular studies have demonstrated that some cellular events, such as c-jun N-terminal kinase (JNK) pathway activation, endoplasmic reticulum (ER) stress, and mitochondrial oxidative stress may play important roles in the development of hepatitis. Herein, the molecular mechanisms of APAP hepatotoxicity are summarized. We also discuss the not-so-familiar “dark side” of APAP as an otherwise safe analgesic/antipyretic drug.

Acetaminophen (paracetamol, N-acetyl-p-aminophenol; APAP) is undoubtedly a
well-recognized and highly used antipyretic/analgesic in the world. However, some
experts have misunderstood that APAP is a type of non-steroidal
anti-inflammatory drugs (NSAIDs) with weak-to-moderate effects, since the
adverse reaction profiles of APAP described in package insert in Japan are
almost the same as classical NSAIDs. Even clinicians and researchers might
actually have a wrong perception regarding it. The review by Ishitsuka et al. the
safety profiles of APAP particularly in terms of respiratory tract and ductus
arteriosus-related toxicity. We also introduce some recent findings about
molecular mechanisms of APAP hepatotoxicity.

Microbes are important for pharmacists,
biologists, and chemists, because some environmental microbes cause infectious
diseases, but also produce beneficial compounds for our health. Understanding
environmental microbes are necessary to live with them and also contributes to
preventing infectious diseases. This current topic summarized the recent
progress on controlling environmental pathogenic microbes by disinfection
methods, sterilization methods, vaccines, antibiotics, and developing new
technologies.